Screw thread lock



Feb. 16, 1932. E. R. LLEWELLYN SCREW THREAD LOCK Filed June 3 1930 screws to become loose.

Patented Feb. 16, 1932 UNITED STATES PATENT OFFICE ERNEST R. LLEWELLYN, OF ARLINGTON, MASSACHUSETTS, ASSIGNOB TO THE HENDEY CUT MACHINE COMPANY, OF TORBINGTON, CONNECTICUT, A CORPORATION OF CONNECTI- SCREW THREAD LOCK Application filed June 80,

' This invention relates to screw threads and more particularly to means for preventing relative rotary motio. between two threaded members, and while not limited thereto is particularly adapted to locking an externally threaded screw in an internally threaded member.

It is well known that the camming action of a screw thread will, under vibration, cause a screw to become loose and to back out of a tapped member. To overcome this action to some extent it has been necessary to hold a very limited tolerance between the screw thread and the tapped member and while this is a costly operation its effectiveness is not assured. Another general practice has been to secure a screw in a tapped hole by means of superimposing a so-termed jamb-screw after the first screw has been positioned. This is in accordance with the check nut theory. This practice is not advanta eous when it is desired to obtain a required a justment of the first screw as the tightening of the jamb-screw has a tendency, when it comes in contact with the first screw, to rotate and tighten the first screw. It is also possible for the above camming action to cause both of this practice it is often necessary to use a larger diameter amb-screw which requires an additional drilling and tapping operation.

To overcome the above disadvantages my locking device is contained permanently within the screw as is best illustrated by a fillister or headless screw wherein a screwdriver is inserted into a slot to rotate the screw. When the screw-driver is inserted into the screw slot, the locking device is actuated and disengaged from the internally threaded member. As the screw-driver is withdrawn from the screw slot my locking device automatically engages with the threaded portion of the internally threaded member thereby locking the two members in position In the application I 1930. Serial No. 485,052.

thus preventing further relative rotary mo-, tion between the two members.

The object of my present invention is to provide a self-contained locking screw that may be positioned in a tapped member and when so positioned further relative rotary movement is arrested.

With the above and other objects in view my invention consists in a novel combination and arrangement of parts hereinafter described and more specifically pointed out in the appended claims.

In the accompanyin drawings I have i1- lustrated my device su icient to enable those skilled in the art to understand the construction and operation thereof.

Referring to the drawin Fig. 1 is a vertical section of a fillister head screw having my locking device contained therein.

Fi 2 is a view corresponding to Fig. 1, but s position.

Figs. 3 and 4 are modifications of my locking device.

Fig. 5 shows my locking device contained in a headless socket screw.

In the drawings I have shown a member 10 having an opening 11 internally threaded to receive the threaded portion 12 of the screw body. 13. The screw is provided, in this instance, with an enlarged head 14 having a, transverse slot 15 adapted to have inserted therein a screw-driver 16.

The body portion 13 of the screw is provided with a chamber 17 which connects with the slot 15 thru a communicating opening 18 which is of a less diameter than the chamber 17 Slidably mounted in the chamber 17 is the enlarged portion 190 of the plunger 19 which extends thru the o ening 18 and into the slot 15. The lower portion 19b of the plunger engages a resilient transverse member 20 the ends of which have their hearings in oppoows the locking device in a. different of the plunger thus retaining the plunger in its normal inoperative position, as shown at Fig. 1, and permitting the resilient trans verse member threads in the member 10.

At Fig. 2 the plunger 19 by a screw driver 16 thus actuating the mem;

ber 20 and retracting the ends of said mem' her from engagement with the internal threads of the member 10. l

At Fig. 3 I have shown a modification of the resilient transverse member Q2which :has a substantially U shaped section with lateral extending ends proiecting thru, the openings 12a. in the threaded portion 12 ofthescrew, and normally engage "with the internal threads of the member 19. TheinemberQQ is actuated by the plunger 19 as above deseril Fig. i ilii-istrates n further-Jnodification, the resilient member 23 being provided with the oppositely disposed endsofwhich "a :t than the Openings 1% and nom nally engage with the internal threads of the mem- 10. The member 23 is actuated by the plunger 19 as previously mentioned.

At 5. i have, shown my lockingdevice as applied to a headless .screw 24. iln this particular instance the outer end of he screw evided with en opening 25 adaptedto e inserted therein a wrench, 26. As the h S inserted in the opening 25, the er if depre... 4. thus actuating the member 28 and disengaging re ends her from engage t with. the inthe 'i'nemher 2%.

' iiied my invention it will ill .rous changes and niodiions may we made therein by those siriiled departing from the spirit thereof, therefore "I do not wish ed to the specific details disclosed,

threaded element, resilient means ins-d; within sid externally tiire. etl

extending thereti i internally ve tary isn't-s,

is shown" it verse member supported in said externtlly threaded element and normally extending therefrom to engage the threads of said internally threaded element to prevent relative rotary movement between the two said elements after the elements have been relatively positioned, eoacting means to retain said transverse member ino erative during the positioning of the two said elements.

In testimony whereof I have hereunto set y h d i ll" .1

' ERNEST-R. LLEWELEYN.

20 to engage with the internal 

